Kinematic Validation of a Robotic Exoskeleton for Assisting Seated Pelvic Movements by Wheelchair Users with Trunk Impairments

Individuals with severe impairments in trunk control have difficulty maintaining and controlling upright posture during static or dynamic sitting. Passive devices like straps and orthoses may be used currently to support the trunk in a wheelchair at the expense of user mobility. Alternatively, we propose that an active support to the pelvic segment may enhance daily activities while maintaining stability on the seat. This paper presents a kinematic validation of a fabricated robotic device for pelvic assistance on a wheelchair, and we name this device as a pelvic Wheelchair Robot for Active Postural Support (pWRAPS). The robot has an in-parallel architecture with three rotational degrees-of-freedom (DOFs). The end-effector translation is also coupled with the rotation to accommodate the natural movement of the pelvis on the seat. The device was tested with seven healthy subjects to evaluate the workspace provided by the device compared to their natural range of motion (ROM). The position accuracy of the device was also validated against a virtual reality (VR) motion tracking system.